Apparatus for demonstrating the strains in building constructions.



No. 871,861. PATENTED NOV. 26, 1907.

' E. CARLIPP. APPARATUS FOR DEMONSTRATING THE STRAINS IN BUILDINGGONSTRUGTIONS.. APPLICATION FILED JAN. 2. 1007.

2 SHEETS-SHEETI 1.

uuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuu c.

No. 871,861. PATENTED NOV. 26, 1907.

GONST'RUUTIONS.

APPLICATION FILED JAN. 2. 1907.

2 SHEETS-SHEET 2.

0 WW Wm WM a ERNST OARLIIP, OF ERLANGEN, GERMANY.

APPARATUS FOR DEMONSTRATING THE STRAINS IN BUILDING CONSTRUCTIONS.

Specification of Letters Patent.

Patented Nov. 26, 1907.

Application filed January 2, 1907' Serial No. 350-421- To all whom itmay concern:

Be it known that I, ERNST CARLIPP, engineer, subject of the GermanEmperor, residing at Erlangen, Bavaria, Germany, have invented new anduseful Improvements in Apparatus for Demonstrating the Strains inBuilding Constructions, of which the following is a specification.

This invention relates to a model for demonstrating the strains arisingin building constructions. In order to render these visible theconstructional parts, according to this invention, are composedalternately of solid pieces and adjustable springs, so that from thealteration of form of the latter the distribution of pressure may beconcluded or ascertained.

The model does not only serve for demon strating the kind of strain andapproximately its degree or extent, but also the alteration of thestrains with variable loads, and, when the load remains uniform, the

' alteration of the distribution of the strain which takes place inconsequence of the elastic alteration of form of the constructionalparts.

Three models are shown as an example in the accompanying drawings; inwhich 2-- Figures 13 show a simple model for support; Fig. 7 is asection of the line BB of Fig. 5; Fig.- 8 shows one device for fixingand adjusting the springs.

WVith a load in the center line of the apparatus (Fig. 1) the springs 2are only compressed, so that the solid parts 1 are displaced parallelwith their original positions; in the case of a load out of the centerline of the apparatus (Fig. 2) bending strains also arise. In similarmanner compressive and torsional strains may also be demonstrated.

Fig. 3 shows a plan view of the arrangement of the springs, the numberof which may of course vary.

The model shown in Figs. 48 may be used for demonstrating thealterations of the strains arising even with a uniform load, in

, consequence of the alteration of form of the constructional parts andits supports. This is particularly important because statlc calculationscan always be carried. out only for a given condition of the respectivecon.- struction, but by the model the possibility is allorded of judgingin what manner variations from the assumed condition apply to thedistribution of pressure.

The left hand support of the arch carrier is fixed, the right handsupport is formed by a beam 3 running with rollers 4 and 5 on rails 6and 7, which beam consists of two bars held together by bolts and aheadpiece mounted on it, revoluble on a shaft 8. The rear end of thebeam 3 bears against a cushion formed of springs 11 and a fixed or solidpiece 10, while the headpiece 9 is exposed to the action of a spring 13engaging against a support 12. The parts 10, 11 and 13 may be replacedby rigid parts for the purpose of making the support a fixed one. Atraetivc force may be exerted on the beam 3, in addition to that exertedby the springs, by a weight 15 which hangs 011 a cord running over theroller 14-, and a turning action 011 the headpiece 9 by means of aweight 17 which hangs on a cord running over a wheel 16. Forcounterbalancing the weight 17 which loads the beam 3, one sidedly, acounterweight 18 (Fig. 6) is employed.

N ow in order to demonstrate the tensile displacements arising inconsequence of the elastic alterations of form, the support is firstfixed and the arch abutment loaded. Alterations of form then result inthe spring parts 2 of the arch, from which the way in which the strainsare distributed becomes apparent. For instance, when the load remainsconstant, not only will compressive strains be indicated such as wouldresult from the calculation disregarding the elastic shortening of thecenter line of the arch, but also bending strains will be shown. Theapplication of solid counter-supports corresponds to an assumptionusually lying at the basis of a static calculation. Now if the supportbe released so that it can yield elastically against the action of thesprings 11 and 13, this case corresponds to the actual elastic yieldingol' the support, and in spite of the load remaining uniform there alwaysappear, as compared with the first case, substantial dill'erences in thedistribution of pressure in the arch abutments, from which differencesthe reliability of the results of the calculation may be concluded.

In order to obtain an idea as to the dependence of the alterations ofthe pressure and the ressure on the supports connected therewit 1, ofvarious sized displacements and twisting movements of the support,weights 15 and 17 are employed after the springs 11 and 13 have beenremoved.

The alterations of ressure in the arch abutments are particu arlyclearly shown if they are coated with plaster or the like. The places atwhich cracks are formed on an alteration of the weight load, and thewidth of these cracks, then afford a clear picture of the displacementof the pressure in the arch abutments.

An arrangement for adjusting the springs is shown in Fig. 8. Recesses 19are provided in each intermediate piece 1, which recesses are coveredwith annular disks 22 screwed thereon. The inner edge of these disksengages in a sleeve consisting of the parts 20 and 21 which consequentlycan turn but not be displaced. It is provided Withan inner .thread inwhich the spiral springs are screwed by turning the sleeve and so may besuitably adjusted. The strength of the springs corresponds to theco-eflicient of elasticity of the material of the abutment support. Byinserting springs of different strength the behavior of compositebuilding materials such, for instance, as ferro-concrete and the like,may be demonstrated.

Of course models of the kind hereinbefore varied cases. They are mainlyintended to be employed for instructional purposes in teaching staticsand the theory of elasticity, they may also, however, be directlyemployed for judging the distribution of forces in constructions, whichare with difficulty accessible to static calculation, and to which theyare adapted or formed.

I declare that what I claim is 1. An apparatus for demonstrating thestrains arising in building construction, comprising a plurality ofelements, said elements consisting of alternately arranged springs andblocks, said springs indicating by their change of form the distributionof strains.

2. An apparatus for demonstrating the strains arising in buildingconstruction, comprising a pair of opposing abutments, a plurality ofelements lnterposed between said abutments, comprising alternatelyarranged yielding and non-yielding members, which by their change inform demonstrate the distribution of strains, and means for supportingone of the abutments so as to permit it to have a pivoting and also alateral yielding movement, substantially as described.

In testimony whereof I have signed my name to this specification in thepresence of two subscribing witnesses.

ERYST CARLIPP.

